The electrolysis of ionizable chemical compounds, e.g., alkali metal halides, to yield useful products, e.g., alkali metal hydroxides, hydrogen and the elemental halogen has long been practiced commercially. The electrolysis has been carried out in diaphragm cells wherein there are two compartments separated by a porous diaphragm. One compartments contains the cathode and the other contains the anode, the electrolyte flowing from the anode compartment through the porous diaphragm into the cathode compartment completing the electrical circuit. A variant of such a two-compartment cell, i.e., the filter press arrangement, wherein a number of cells are connected in series in a common housing. In such a variant, the anode of one cell is connected electrically with the cathode of an adjacent cell, said cells being separated by a barrier serving to prevent the passage of electrolyte between the adjacent cells. Such a configuration is termed a "bipolar electrode" and the series of cells is called a "bipolar type filter press cell."
The provision of efficient electrical connections between the anode and cathode elements of adjacent cell units which are both compact and liquid and gas tight is an important and often troublesome problem in the design and fabrication of bipolar type filter press cells. In some cells, the electrical connection is accomplished by external wiring which is not only expensive in the amount of metal required but also relatively difficult to maintain in leakproof condition. In other installations, as disclosed for example in U.S. Pat. No. 3,242,059, expensive titanium is used as both the individual cell divider and electrical connector. In U.S. Pat. No. 3,752,757, there is provided a bipolar electrode unit, including a plastic barrier sheet separating the adjacent cell units. The anode and cathode units are connected though bosses attached to the electrodes and maintained in axial alignment by means of a bolt extending through said bosses. The sealing of the cell is accomplished by O-rings set in chambers cut in each of the bosses. Such a design wherein dissimilar metals are placed in contact with each other requires careful fabrication and due to differences in the coefficient of expansion are difficult to maintain in fluid-tight condition during extended use. Accordingly, it can be seen that available electrical connectors for bipolar electrodes currently available leave something to be desired.